Apparatus for the receipt of wireless impulses



May 29, 1923. 1,456,867

F. CONRAD APPARATUS FOR THE RECEIPT OF WIRELESS IMPULSES FilQ m y 15 1919 2 Sheets-Sheet l WlTNESSES: INVENTOR KJMW Fran/r w/imd F. CONRAD APPARATUS FOR THE RECEIPT OF WIRELESS IMPULSES May 2 9, 1923.

Filed May 15 1919 2 Sheets-Sheet 2 INVENTOR Fran/r Can/"00 w TTOR N EY WITNESSES: ff GYM/"1W (9 gam Patented May 29, 1923.

UNITED STAT.

OFFICE.

FRANK CONRAD, OE PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

APPARATUS FOR THE RECEIPT OF WIRELESS IMPULSES.

Application filed May 15,

To all whom it may concern. v

Be it known that I, FRANK CONRAD, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Ap )aratus for the Receipt of Wireless lmpuises, of which the following is a specification.

My invention relates to apparatus for the receipt of wireless impulses and it has for its object to provide apparatus of the character designated that shall enable one to distantly control relays or other forms of electrical apparatus by means of wireless im-- pulses and, at the same time, to substantially prevent the operation of such apparatus by other than the impulses intended therefor.

Fig. 1 of the accompanying drawing is a diagrammatic view of a system embodying my invention, being shown for the wireless control of a distant relay; Fig. 2 is a diagrammatic view of a modified form of relay that may be used in the system of Fig. 1; and Figs. 3 and 4 are views similar to Fig. 1 and illustrating modifications in the system thereof.

It is frequently desirable to control apparatus at a distance by wireless impulses, as, for example, in the wireless control of torpedoes. In the past, difficulty has been encountered in obtaining a clear and distinct receipt of the transmitted impulses, particularly under adverse circumstances, as where hostile forces are filling the ether with impulses of various wave lengths and group frequencies for the specific purpose of preventing the wireless control of torpedoes and similar apparatus.

I I find that very effective control of relaysor similar apparatus may be secured by providing a hot-cathode tube in the eleotrical connection to the relay to be controlled and by continuously supplying to said tube an electromotive force slightly below its critical voltage. The incoming impulses are then superposed upon the electromotive force in the form of transient voltage increments, the resultant voltage being suflieient to pass above the critical voltage of the tube, permitting the passage of relatively large amounts of current therethrough and to .the relay to be controlled. 7

With a system of this character, it'will be obvious that there'is a'tendenc to pass a small amount of current throng the relay 1919. Serial No. 297,314.

at all times but I find that, by shunting the relay with an auxiliary source of electro motive force, the potential conditions of the circuit may be so adjusted that no current flow whatsoever takes place through the re lay except when impulses are being received upon the antenna.

In order to render an impulse-receiving system of this character highly selective, I find that it is desirable to dynamically interlink the relay with the antenna through two local circuits, one of which is tuned to resonate to the radio frequency and the other of which is tuned to resonate to the spark or group frequency.

Under these conditions, it is substantially impossible for the enemy to deflect the approaching torpedo by sending out impulses from his own station, as it is necessary not only that he employ the same wave length or radio frequency but that he simultaneously employ the same spark or group frequency and that the spark or group frequency impulses be'substantially in syn chronism with the impulses from the station controlling the torpedo. v

For a more detailed understanding of my invention, attention is directed to Fig. 1 wherein 6 designates a piece of apparatus to be controlled, such, for example, as a relay controlling the steering circuit 7 of a torpedo.

The relay 6 is connected to be subject to the control of impulses received at an antenna 8, the ground lead of this antenna including the primary winding 9 of a loose coupling transformer 10. The secondary winding 11 of the transformer 10 is connected to supply energy to the anodes 12 and 13 of a hot-cathode rectifier 14, fur' ther embodying a hot cathode 15. The cathode 15 is maintained at incandescence by an A battery 16 and is connected to one terminal of the relay 6 through a current source 17, attention being directed to the fact that the positive terminal of the current source is connected directly to the relay.

The remaining terminal of the relay 6 is connected to substantially the midpoint of the secondary winding 11 and a current source 18 is connected in shunt relation to therelay 6 through an adjustable resistor 19, attention being directed to the fact that connected to the same terminal of the relay 6 as is the positive terminal of the current source 17.

In operation, the voltage of the battery 17 is adjusted so as to impress a voltage upon the rectifier 14 slightly below the crltlcal voltage thereof or, in other words, a voltage just insuflicient to draw electrons from the cathode 15 to the anodes 12 and 13. This condition is attainable with any form of hot-cathode rectifier but more readily at tainable with those filled, to a greater or less extent, with inert gases, such as mtrogen or argon.

With the conditions just set forth, it is apparent that a slight current flow tends to take place from the positive terminal of the battery 17 through the relay 6 to the mldpoint of the secondary winding 11 and thence, through the anodes 12 and 13, to the cathode 15 and back to the negative terminal of the source 17, this current flow tending to operate the relay 6. The potential of the source 18 is so adjusted as to bring the potential of the positive terminal of the battery 17 to the point that the upper terminal of the relay 6 would have were the source 18 not present or, in other words, the battery 18 tends to equalize the potential of both terminals of the relay 6 with respect to the source 17. Under these conditions, all current tending to flow from the source 17 is shunted through the source 18 and does not traverse the relay 6.

Let it now be assumed that incoming impulses are received on the antenna 8 of such character as to be responded to thereby. These impulses produce an alternating electromotive force I in the secondary winding 11 and this electromotive force is rectified by the device 14 in such manner as to superpose periodic impulses upon the voltage of the source 17. The resultant effective electromotive force in the circuit is higher than the critical voltage of the device 14 and thus relatively large currents flow therethrough. The modified TR drop in the device 19 so disturbs the potential distribution within the system that a portion of the increased current flow traverses the relay 6, operating the same in the desired manner.

In the system of Fig. 2, an alternative form of relay is shown, comprising two operating windings 21 and 22. The wind ing 21 corresponds to the winding of the relay 6 in the system of Fig. 1, and the winding 22 is connected across the terminals of the source 17 through a resistor 23.

Under normal operation. in the absence of control impulses, the leakage current through the rectifier traverses the winding 21-, and the resistor 23 is'so adjusted that the current traversing the winding 22 from the source 17 roduces an equal and oppoessee? site magno-motive force in the relay, so that no flux is produced therein. In other words, in the inoperative position there is a magnetic neutralization of the operating relay, whereas, in the system of Fig. 1, there is a potential neutralization thereof.

Upon the receipt of control impulses, the voltage tending to force current through the winding 21 is increased, whereas that tending toforce current through the winding 22 remains the same. Consequently, the magnetic conditions within the coils of the relay 20 are unbalanced, and a sufficient operative flux appears to cause the desired operation.

Referring to the form of apparatus shown in Fig. 3, particular attention is directed to the selective features, whereby it is rendered exceedingly diificult to control the desired apparatus by any but an operating station properly adjusted thereto. The antenna 8 energizes a loose-coupling transformer 10, as before, and the secondary winding of this transformer is connected in a local circuit including a shunting condenser 30 and the grid 31 and hot cathode 32 of the hot-cathode detector 33. The condensance of the capacitance device 30 is tuned with the inductance of the transformer 10 so that this first local circuit resonates at radio frequency, the modulations in the potential of the grid 31 permitting current flow from a current source 34 between a plate electrode 35 and the cathode 32. This current flow takes place through a second local circuit embodying an inductive reactor 36 and a condenser 37, these elements being adjusted so that the second local circuit resonates at the spark or group frequency of the incoming impulses.

impulses of such character as traverse both local circuits affect the potential of the grid electrode 40 of an additional hotcathode detector 41 embodying a plate electrode 42 and a hot cathode 43.

The modulation of the potential of the grid electrode 40 permits pulsating current flow from a current source 44, and these pulsations are rectified in a hot-cathode rectifier 1 45 for transfer to the relay 6, this relay being provided with the same potential control as in the system of Fig. 1 to prevent the fiow of rectifier leakage current therethrough when impulses are not being received.

By the, specific arrangement of local circuits described, it will be obvious that it is exceedingly difiicult for unauthorized or hostile persons to control the relay 6.

The system of Fig. 4 is largely similar to that of Fig. 3 except that an additional plate electrode 50 is placed within the detector bulb 41, whereby this bulb is caused to perform the functions of the bulb 41 and of the rectifier 45 in the system of Fig. 3. The normal plate electrode 42 is connected to the hot cathode 43 through a current source 44 and an inductive reactor 45'. The relay 6 is connected between the junction point 46 of the source 44 with the reactor 4-5 and the auxiliary plate electrode- 50. The modulation of the potential of the grid electrode 40 permits the flow of current impulses from the source 44, thus causing the potential of the point 46 to oscillate. These oscillations arerectified between the plate electrode 50 and the hot cathode 43, producing unidirectional current impulses in the relay 6 for the operation thereof.

While I have shown my invention in a variety of forms, it will be obvious to those skilled in the art that it is susceptible of still other changes and alterations without departing from the spirit thereof and T desire, therefore, that only such limitations shall be placed thereupon as are imposed by prior art or are specifically set "forth in the appended claims.

I claim as my invention:

1. In a system for the wireless control of electrical apparatus, the combination with a source of electrical energy in proximity to said apparatus, of a hotcathode tube connected therebetween, the voltage impressed upon said tube by said source being slightly below the critical voltage thereof, receiving means for the transmitted control impulses, said receiving means impressing said impulses upon said source to produce transient voltage increments thereof, said tube operating above its critical voltage during the passage of said increments and permitting largely increased flow of current to said apparatus, and means for shunting the relatively slight current tending to flow through said apparatus therearound in the absence of said voltage increments.

2. In apparatus for the wireless control of electrical apparatus, the combination with an antenna for the receipt of the transmitted cont'rol impulses, of a local circuit dynamically interlinked therewith and tuned to resonate to the group frequency of the transmitted impulses, a local source of current connected to the apparatus to be controlled through a hot-cathode tube subjected to slightly less than its critical voltage from said source, means for adding voltage impulses to the voltage of said source in accordance with the impulses passing through said local circuit, whereby said tube is caused to operate above its critical voltage and to permit the passage of relatively large current to said apparatus, and means for shunting the relatively slight current tending. to flow through said apparatus, when said tube is operating below its critical voltage, around sald apparatus.

3. In apparatus for the wireless control of electrical apparatus, the combination with an antenna for the receipt of the transmitted control impulses, of a local circuit dynamically interlinked therewith and tuned to resonate to the radio frequency of the transmitted impulses, an additional local circuit connected in cascade therewith and tuned to resonate at the spark frequency of the transmitted impulses, a local source of current connected to the apparatus to be controlled through a hot-cathode tube subjected to slightly less than its critical voltage from said source, 11 ans for adding voltage impulses to the voltage of said source in accordance with the impulses passing through said local circuits, whereby said tube is caused to operate above its critical voltage and to permit the passage oi. relatively large currents to said apparatus, and means for shunting the relatively slight current tending to flow through said apparatus, when said tube is operating below its critical voltage, around said apparatus.

4. A signaling system comprising, in combination, a translating device for responding to signal impulses, a source of normally substantially constant current therefor, means for causing said current to vary in accordance with electrical signal impulses, and a shunt circuit for said translating device, said shunt circuit including an auxiliary source of elcctlromotive force and having an impedance of such value that the elcctro motive force drop resulting from said impedance when said shunt circuit is carrying said normal current is substantially equal and opposite to the electromotive force of said auxiliary source.

5. The combination with a controlling circuit carrying a current subject to departure from a predetermined value in the presence of signal currents, of a translating device serially included in said circuit, and a shunt circuit for said translating device, said shunt circuit including an auxiliary source of electroniotive force and having an impedance of such value that the electromotive force drop resulting fron'rsaid impedance when said shunt circuit is carrying said predetermined value of current is substantially equal and opposite to the electromotive force of said auxiliary source.

6. The combination with a controlling circuit carrying a current subject to departure from a predetermined value in the presence of signal currents, of a translating device serially included in said circuit, and means connected in shunt witl1 said translating device for providingga path of substan tially zero impedance only when current of said predetermined, value is flowing therein;

7. The combination" with a controlling circuit carrying a current subjectto departure from a predetermined value, of a source of electromotive force for assisting the current-flowiin said circuit, an impedance device in said circuit for developing, in conjunction with the internal impedance of said source, a counter-electromotive force which is substantially equal and opposite to the electromotive force of said source, and a voltage-responsive device shunted across said source and impedance device.

8. The combination with a controlling circuit carrying a current subject to departure from a predetermined value in the presence of signal currents, of means for developing an electromotive force for assisting the current-flow in said circuit, means for developing a normally equal and opposite electromotive-force for opposing the. current-flow in said circuit, said two means being unequally related to departures of the current from said predetermined value, whereby the equality of said electromotive forces is disturbed in accordance with said departures, and means responsive to said disturbance of the equality of said electromotive forces. y

In testimony whereof, I have hereunto subscribed my name this 29th day of April,

FRANK CONRAD. 

